Unable to download teams channel pasted image

@David_Chan2255-Thank you for your inquiry about your Teams app development issue! To assist you better, could you please provide the following details?
1.Please share the steps you took to encounter the issue.
2.Any specific documentation you followed that relates to your problem.
This information will help us better understand the situation and provide a more accurate response.  

Also, ensure that the token you are using is valid and has not expired. Tokens typically have a limited lifespan, and using an expired token will result in a 401 error.